After Confucius returned from Wei state to Lu state, he had not been able to take important positions. In his later years, Confucius liked to read The Book of Changes, and wrote ten essays elaborating on it, collectively known as the "ten wings". Confucius read The Book of Changes so frequent that the leather strips connecting the bamboo slips had broken many times. Confucius said humbly, "If I could live for a few more years, I can fully master the text and essence of The Book of Changes. Then I can avoid making big mistakes."